1. Field of the Invention
The present invention relates generally to electronics and particularly to electronics with two-dimensional (2D) and three dimensional (3D) display functions.
2. Description of the Background Art
In recent years mobile terminals, mobile personal computers (mobile PCs), mobile phones and other similar mobile equipment, and desktop or similar information equipment, and furthermore a variety electronics including audio and video equipment are increasingly enhanced in function.
A conventional mobile phone is a 3D display-equipped mobile phone with a 3D display function that can switch 2D and 3D representations for display. For example, as disclosed in Japanese Patent Laying-Open No. 2001-251403, 2D and 3D representations are switched by allowing a lenticular lens arranged above a liquid crystal display corresponding to a display unit to be movable to allow a 2D display portion's display region and a 3D display portion's display region to be changeable.
Normally when a mobile phone is not used as a telephone a screen referred to as an idle screen is set as a default screen. An idle screen can be set by a user, as desired, by selecting an image previously registered, an image obtained via a camera, or an image downloaded at a website, by mail or the like via a browser.
Furthermore, the idle screen displayed on the display can be switched for example by pressing a key to an operating screen or a setting screen, as required.
For the 3D display-equipped mobile phone with a 3D display function as described above, an idle screen displayed three dimensionally is proposed.
With reference to FIGS. 14-19, a configuration of a 3D display switchable between 2D and 3D representations will be described.
FIG. 14 shows a layout of pixels of a liquid crystal device (a liquid crystal display (LCD)) of a standard type. An LCD is used in a color display and configured of pixels of red, green and blue represented by R, G and B, respectively. With reference to the figure, the pixels are arranged in columns Col0 to Col5 formed of red, green and blue pixels arranged vertically. Of the pixels, the leftmost column Col0 displays the leftmost strip of an image displayed by the liquid crystal device and the right-hand column Col1 displays the next column of the image, . . . , and so on.
FIG. 15 shows a display used to provide a 3D stereoscopic representation. With reference to the figure, the 3D display includes a liquid crystal display device 101 (including a polarization plate) acting as a spatial optical modulator adjusting light from a backlight 102 in accordance with content of an image to be displayed. A parallactic optical system cooperates with liquid crystal display device 101 to form a viewing window. FIG. 15 shows a configuration of a 3D, automatic, stereoscopic display of a front parallax barrier type having a parallax barrier 103 as a parallactic optical system. Parallax barrier 103 includes a plurality of slits extending vertically and laterally equally spaced and also arranged in parallel. Each slit is located at a center of a pair of columns of pixels of a color and that of pixels of a different color. For example in FIG. 15 a slit 104 is located at a center of a blue pixel column 105 and a green pixel column 106.
To ensure that right and left viewing windows are properly arranged, right and left image data are supplied by the method shown in FIG. 16 to liquid crystal display device 101 of the FIG. 15 type. In FIG. 16, color image data of a leftmost strip of a left image is displayed by a red, green and blue pixel column Col0 LEFT. Likewise, color data of a leftmost strip of a view for the right eye is displayed by a pixel column Col0 RIGHT. The FIG. 16 arrangement ensures that right and left views' image data are sent to appropriate right and left viewing windows. This arrangement also ensures that three pixel colors R, G, B are all used to display each view strip.
Thus in the FIG. 16 layout, as compared with the FIG. 14 layout, the leftmost column's red and blue pixels display a left view's image data while the same column's green pixel displays a right view's image data. In the right-hand column, red and blue pixels display the right view's image data while a green pixel displays the left view's image data. Thus if a liquid crystal display device of a standard type shown in FIGS. 14-16 is used, it is necessary to “exchange” a green component between RGB pixel columns to interlace right and left views' image data. It is a matter of course that for some display settings, red or green component may be exchanged.
FIG. 17 shows a configuration of a portion of a display controller. With reference to the figure, data to be displayed is supplied on a data bus 120 serially. An address that defines an arrangement on a screen of pixel is supplied on an address bus 121. Data bus 120 is connected to an input port of several banks of memory (video random access memory (VRAM)) 122, 123 or similar RAM (in FIG. 17, two such memories are shown). Address bus 121 is connected to a memory management system 124, which converts a screen address to a memory address supplied to an address input of memory 122, 123.
Memory 122, 123 has an output port connected via a latch circuit 130 to a first in first out (FIFO) register 124 of a video controller 126. Memory 122, 123 and register 125 are so controlled that individual pixel data are read from memory 122, 123 alternately and supplied in a proper order to a display memory (VRAM) 127 located between the display controller and liquid crystal display device 101 to serve as a memory for display temporarily storing data to be displayed that have been rearranged.
FIG. 18 shows latch circuit 130 more specifically. With reference to the figure, latch circuit 130 includes a latch 140 connected to an output port of memory 122 and a latch 141 connected to an output port of memory 123. Latch 140, 141 each includes 24 1-bit latches arranged in groups of eight latches to latch R, G, B data received from their respective memories. Latch 140, 141 has an input port connected to an output port of timing generator 128 to receive from timing generator 128 a plurality of latch enable signals L at a single input port collectively.
Latch circuit 130 further includes three switching circuits 142, 143, 144 corresponding to R, G, B data, respectively, and switching a connection between register 125 and latch circuit 140 or 141. Switching circuits 142, 143, 144 each include eight distinct switching elements each receiving a plurality of control inputs collectively. Switching circuit 142, 143, 144 has an input port connected to an output port of timing generator 128 to receive from timing generator 128 a plurality of control inputs, a switching signal SW, at a single input port collectively. Timing generator 128 has an additional output port to supply a write enable signal F with register 125. Herein, it should be noted that switching circuit 143 corresponding to G data switches to one of latch circuits 140, 141 while the other switching circuits 142, 144 switches to the other of the latch circuits.
If data to be displayed is available at the memory 122, 123 output port, latch enable signal L attains the high level. Thus latches 140, 141 latch the data. Immediately after latch enable signal L returns low, switching signal SW goes high. Then, switching circuits 142, 143, 144 are switched as shown in FIG. 18 and latch 140 and register 125 are connected together to allow latch 140 to have R, G, B data output to register 125. Subsequently, write enable signal F is supplied to register 125 and the RGB data from latch 140 are written to register 125. Subsequently, write enable signal F is rendered unavailable to prevent further data from being written to register 125 before a subsequent write enable signal is issued.
Then, switching signal SW is set low and switching circuits 142, 143, 144 connect latch 141 and register 125 together to allow latch 141 to have R, G, B data output to register 125. Further write enable signal F is generated and the data from latch 141 are written to register 125. Note that the data having written to register 125 is concurrently written to memory 127. Subsequent latch enable signal L goes high and a similar process is repeated. Thus data are written from memories 122, 123 alternately to register 125. Memory 127 also receives written data from register 125 and has the data written therein successively. This repeats until data required to display a single screen are all written in memory 127.
2D data or a monoscope's data that must be displayed for a viewer's both eyes is written to memory 127, as follows: in that case, the parallactic optical system by means of parallax barrier 3 is removed. A monoscope's pixel data is directly input to and stored in memory 127 for display shown in FIG. 17 to perform a write to memory 127. In a 3D display mode, an image for the right eye and that for the left eye each has a resolution corresponding to a half of a horizontal spatial resolution of liquid crystal display device 101. Accordingly, if the display controller operates in a 2D or monoscope mode, an image, as compared with a 2D image, will have a resolution twice a lateral resolution of liquid crystal display device 101.
Note that the parallactic optical system may be formed selectively. FIG. 19 shows a specific example of a display device so configured that the parallactic optical system's selective formation allows 2D and 3D images to be electrically switched and displayed. Herein, for the parallactic optical system, for example for the above a 2D/3D switching liquid crystal device LCD 150 and a patterned phase different plate 141 such as shown in the figure are used. Liquid crystal device 150 herein is a flat electrode for switching an entire surface to 3D, 2D. Phase difference plate 151 replaces one of two polarizing plates included in the liquid crystal device. In FIG. 19, a portion substantially identical in function to that shown in FIG. 15 are labeled identically. While in the FIG. 19 example a parallax barrier 103a is arranged at a rear side of liquid crystal display device 101, i.e., closer to a backlight 102, the barrier 103a may be arranged at a front side of the device 101, as shown in FIG. 15.
When the display device configured as shown in FIG. 19 is used to display a 3D image, voltage is not applied to liquid crystal device 150. Thus an internal liquid crystal molecule maintains a rotating state and a slit substantially similar to slit 104 of parallax barrier 103 of FIG. 15 is formed by a characteristic of polarization of light relative to phase difference plate 151 in accordance with the plate's pattern.
When the display device configured as shown in FIG. 19 is used to display a 2D image, voltage is applied to liquid crystal device 150. This liberates the liquid crystal molecule from rotation and phase difference plate 151 is not affected by light input to the plate, whether it may have a pattern or not, so that the formation of the slit is resolved. Thus a 2D image can be displayed.
Alternatively, as described in Japanese Patent Laying-Open No. 5-122733 or 7-236174, a liquid crystal display device including a pair of polarizing plates for switching between 2D and 3D representation may be used and as the device's display pattern a pattern similar to parallax barrier 103 may be rendered displayable and displayed selectively.
Note that in a 3D automatic stereoscopic display with a fixed parallactic optical system, as shown in FIG. 15, with parallax barrier 103 attached thereto, right and left video images to be displayed which are identically provided allow this display to display a substantially 2D image. In this case, however, the display itself still has a parallactic optical system formed therein and in displaying in a 2D image when the user observes the representation it will be affected by the system disadvantageously.
By contrast, a display device selectively forming a parallactic optical system, as shown in FIG. 19, advantageously eliminates an effect of parallax in displaying in a 2D image. More specifically, with a display device configured as shown in FIG. 19, when displaying in a 2D image is selected a device configuration is provided that is substantially similar to a normally used liquid crystal display device, free of a parallactic optical system formed at a portion or entirety of a region for display. Without effect of parallax of right and left, a ready visual observation can be achieved at any position.
Thus for a device switching and displaying each image of 2D and 3D images it is necessary for example to switch an operation of 2D/3D switching liquid crystal device 150 corresponding to a component of a parallactic optical system and also change a configuration of data input to memory 127 for display.
A 3D screen in a device allowing 2D and 3D images to be switched and displayed can be displayed in a 3D format by inputting in a 3D image display mode the data for the right eye to be displayed and that for the left eye to be displayed to a video controller 126 and rearranging the data in the controller.
This is also applied when the 3D image display mode is set and the user selects and reproduces as desired an image previously registered, an image obtained via a camera or the like, or an image downloaded at a website, by mail or the like via a browser.
However, for an alarm time indication or on a phone call reception screen or a mail reception screen mainly displaying characters, a 3D image can prevent ready recognition of the characters. In particular, in phone call reception, mail reception or similarly displaying a large number of characters, a 2D image rather than a 3D image would help the user to recognize the characters and rapidly identify their contents.
Furthermore in such a 3D format an indication needs to be observed in a specific direction. This can be difficult when the user continues to see the indication for a long period of time.
Furthermore, when a 3D stereoscopic representation can be difficult to observe as the user is on a moving vehicle, or it is exhausting to continue to see a displayed 3D image for a long period of time, or the user inherently cannot construct a stereoscopic body in a 3D image in his/her mind, switching the representation to a 2D image and displaying it may be desired. Furthermore, if a representation in a 2D image can be switched to that providing a sense of depth, i.e., that in a 3D image, it would give an impact on the user and provide an enjoyable representation.
Note that a mobile flip phone corresponding to the device has been developed to provide multiple display, and there has been proposed a flip phone with a main display unit used with the phone flip open as well as a subordinate display unit arranged on an external side of the phone and usable with the phone closed.